Crossaster papposus

Geographic Range

North Atlantic and Pacific Coasts: (Himmelman and Dutil, 1991) One can find C. papposus from Alaska to Puget Sound, from the Artic to the Gulf of Maine. (MConnaughey and McConnaighey, 1985) It is common in British waters and in eastern Maine and can often be found in the lower intertidal zone from the Eastport area northward. (Hayward and Ryland, 1995)

Habitat

Crossaster papposus is found on rock bottoms, ranging from the low tide line to approximately 1080' (329m) deep. (McConnaughey and McConnaughey, 1985) It is tolerant of strong sunlight. (Coleman, 1991)

Physical Description

Crossaster papposus ranges from 8" to 14" in diameter. It has many arms (between 8 and 14) the length of one-half its radius. It is scarlet on top with concentric bands of white, pink, yellow, or dark red, and it is white on the underside. Its entire upper surface is sparsely covered with brushlike bristles. (McConnaughey and McConnaughey, 1985) These bristles, called pseudopaxillae, consist of bundles of fine spines atop short stumps. The mouth area is bare, and it has two rows of sucker-tipped sensory tube feet. (Gosner, 1978)

Reproduction

Crossaster papposus, like most sea stars, has separate sexes, and fertilization is external. (Hickman and Roberts, 1995) Sexual reproduction produces lecithotropic larva in late winter. One-year-old individuals measure 1.8 to 4.0 cm in diameter, and there is a 2 cm annual growth increment during the following few years. (Himmelman and Dutil, 1991) Juvenile C. papposus tend to prefer sediment bottoms of the sea. Upon growing to 5cm in diameter, C. papposus migrates to shallow water (4-8cm in diameter) and then, with increasing size, it gradually moves to greater depths. (Himmelman and Dutil, 1991) Like other sea stars, C. papposus can regenerate injured or missing arms, as long as a portion of the central disc, where the arms converge, is intact. (Hickman and Roberts, 1995)

Behavior

C. papposus is highly mobile. Large individuals can cover distances of >5 meters in 12 hours. (Himmelman and Dutil, 1991) C. papposus has been found to disperse widely in order to forage for its mobile prey. As a dominant predator high in its food web, C. papposus has also been influential in dispersal of competitors, affecting distribution of these other asteroid species. (Sloan, 1979) When hungry, C. papposus maeks contact with its prey, retracts its sensory tube feet, then protracts its tube feet to gain height over the prey. This enables it then to "pounce" on its victim, whereupon C. papposus swallows small prey whole or covers large, sessile prey with its body and engulfs it with its evertible stomach. (Coleman, 1991) (McConnaughey and McConnaughey, 1985) (Sloan, 1980)
Defense responses of C. papposus are not much studied, but it has been observed that these starfish restract their sensory tube feet as a defensive response. (Sloan, 1980)

Chemoreception abilities have also been observed in C. papposus. It shows a wide variety of responses to crude extract of prey species and conspecifics. Crossaster papposus has the olfactory (distance chemoreception) ability to sense whole, live potential prey and conspecifics. (Sloan and Northway, 1982)

Food Habits

In its habitat, C. papposus is considered to be the dominant predator, along with Solaster endece, another species of predacious sea star. As a dominant predator, C. papposus plays an important role in determining community structure. (Himmelman and Dutil, 1991) Its abundance and frequent predatory activity suggests that it belongs to an important predatory guild. C. papposus has often been observed feeding on urchins, as well as on numerous other invertebrates, including echinoderms, bivalves, cnidarians, and tunicates. (Coleman, 1991) Cannibalism in C. papposus is rare, observed only after long starvation in captivity. (Sloan, 1984)

Economic Importance for Humans: Positive

Unfortunately, information regarding the economic importance of C. papposus and its value to humans is either not well-studied, not well-documented, or simply inaccessible. As an aggressive predator high on its food web and as an agent of dispersal of both its competitors and prey, C. papposus clearly has a significant impact on its ecosystem.

Other Comments

Among the most beautiful of echinoderms, C. papposus is a bright spot of color in North Atlantic and Pacific waters. It can be readily recognized and differentiated from other sea stars in that it has several more than the standard number or tube feet (five). (Hickman and Roberts, 1995)

Contributors

Heather Grush (author), University of Michigan-Ann Arbor.

Glossary

Atlantic Ocean

the body of water between Africa, Europe, the southern ocean (above 60 degrees south latitude), and the western hemisphere. It is the second largest ocean in the world after the Pacific Ocean.

Pacific Ocean

body of water between the southern ocean (above 60 degrees south latitude), Australia, Asia, and the western hemisphere. This is the world's largest ocean, covering about 28% of the world's surface.

coastal

the nearshore aquatic habitats near a coast, or shoreline.

ectothermic

animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature

native range

the area in which the animal is naturally found, the region in which it is endemic.

Disclaimer:
The Animal Diversity Web is an educational resource written largely by and for college students. ADW doesn't cover all species in the world, nor does it include all the latest scientific information about organisms we describe. Though we edit our accounts for accuracy, we cannot guarantee all information in those accounts. While ADW staff and contributors provide references to books and websites that we believe are reputable, we cannot necessarily endorse the contents of references beyond our control.

This material is based upon work supported by the
National Science Foundation
Grants DRL 0089283, DRL 0628151, DUE 0633095, DRL 0918590, and DUE 1122742. Additional support has come from the Marisla Foundation, UM College of Literature, Science, and the Arts, Museum of Zoology, and Information and Technology Services.